The High Court, sitting as the Court of Disputed Returns, found on Tuesday that the Sports Party's Wayne Dropulich and the Greens' Scott Ludlam were not duly elected but could not say who was elected in their place after more than 1300 voters were lost.

Justice Kenneth Hayne declared that because 1370 ballots disappeared between the vote and recount those voters were effectively "prevented from voting".

He said the number of missing votes had substantially exceeded the margin between the candidates at a key point early in the count that resulted in Mr Ludlum and Mr Dropulich being elected ahead of Labor candidate Louise Pratt and Palmer United Party’s Zhenya ‘‘Dio’’ Wang.

The court will sit again on Thursday where it will consider further arguments and issues such as costs of a fresh election.

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Justice Hayne rejected a submission from Mr Wang that the original count should stand or that the result could be determined by comparing results from the count and recount.

"It is neither relevant not necessary to undertake that consideration because the court must find that Mr Dropulich and Senator Ludham were not duly elected, but cannot declare who was elected," Justice Hayne said.

"The only relief appropriate is for the election to be declared void," he said in his judgment.

Constitutional law expert, George Williams made it clear that the court had not ordered a fresh election at this stage, as had been reported by some media outlets.

But he said the findings on Tuesday made another election very likely.

"I think you could say the writing is on the wall," Professor Williams said.

In a statement on Tuesday, the Australian Electoral Commission noted that a fresh election could only occur once a writ has been issued by the Governor of Western Australia, Malcolm McCusker. The writ would outline key dates including for the close of the electoral roll, candidate nominations, and for election day.

Senator Ludlam told reporters outside the court in Melbourne that he thought Justice Hayne had made the "right call" on Tuesday.

"It's inappropriate to disenfranchise 1300 people who voted in a free and fair election, he said.

The Greens senator who was not elected in the first WA senate count but elected in the recount, said that he believed that "the most likely outcome" would be that WA went back to the polls for a fresh election.

He also welcomed the opportunity for federal politics to be seen through the "lens" of Western Australia, rather than western Sydney.

ABC election analyst Antony Greens said that the WA governor would issue the writ for any new WA senate election, "presumably on the advice of the Prime Minister through the Governor-General".

Palmer United Party leader Clive Palmer called on electoral commissioner Ed Killesteyn to resign "over the fiasco" of the WA vote.

Mr Palmer said that "millions of taxpayer dollars" would be wasted "due to the incompetence of the Australian Electoral Commission," he said.